Electric heating furnace



Dec. 11, 1923. 1,411,454

` H. SEIBERT ELECTRIC HEATING FURNCE Filed Aug. 16 1925 Patented Dee.11. 1923.

"UNITED STATES -Mammun..-

HEI'RCH SEIBERT, GF BERLIN, GERMNY.

ELECTRIC HBA TNG FURNAUE.

Application led August 16, 1925i. Serial No. 657,775.

.To all @claw/tit lmay concern.:

Be it known that I, HEINRICH Salaam', a lcitizen of the German.Republic, residing at Berlin, Germany, have invented certain new anduseful Improvements in Electric Heating Furnaces, for which I have filedapplications for' patent in Germany, Feb. 16, 1922, and March 8, 1923,and of which the following is a specification.

This invention relates .to electric heating furnaces with granularresistance material. In these electric furnaces, especially in mufflefurnaces, amuiile exists around which the resistance material is accommddated in hollow4 spaces. The use of such inutiles especially in largersized .furnaces requires corresponding thickness of the wall `even ifthe muilies are composed ot' several parts. The material from which themuiiies are made, namely, lire brick, is apoor conductor of heat, andconsequently is a serious obstacle in the transmission of heat producedin the resistance material to the heat chamber. Especiallyat hightemperatures 0ver.l00O C. it therefore happens sometimes that thetemperature in the heating spaces is higher by several hundred degreesthan the' temperature in the real heating chamber, whereby excessiveheat results in the heating spaces and conse uently damaging of thematerial of the mu e and loss of current. The poor results of suchfurnaces/f' are mainlyy caused by these inconvenience's. y

According/t0 the invention these inconveniences are avoided by formingthe walls of the heating chamber entirely`or partly oit/projectingheating pipes containing ranular resistance material, in order to o tainvthe largest-possible heating surface and to protect at the same timethe 'refractory parts. These heating pipes are preferably built in sothat they are easily exchangeable and eventually non-supported. Theheating pipes may be of convenient cross-section. lf they are ofrectangular cross section and if adjacent faces 'oftwo heating pipes areinclined the one to the other the heat is especially well transmitted tothe inner chamber'. l. i

In order to prevent a mutual over-heat` ing of the heating pipes theyare arranged at a determined distance apart. The air gaps between theheating pipes may extend into the brick work of the furnace. Theyprevent also the production of short-circuits between the pipes.

The heating started and the material of which/.the furi nace is built ispreserved and higher temperatures can be produced with material of equalrefractoriness. l

The invention will be best understood from. a consideration ofv thefollowing detailed description taken in connection with the accompanyingdrawings forming a 'part of this specification, with the understanding"that `while on the drawing several embodi* ments of the invention aredisclosed, the in'- vention is not confined to any strict4 con-' formitywith the showing of the drawings, but may be embodied in any mannerwhich does not make a material. departure from the salienti features ofthe invention.

In the drawing Fig. 1 is a vertical cross sectional view of the furnaceon line AWB of Fig. 3.

F ig. 2 is a vertical longitudinal sectional. view of the furnace on.line C-Dof Fi 3.

iFig. 3 is a horizontal cross section on ine E-1` of Fig. 1. f

. Fig. 4 Shows in plan View the secondform of construction, the topplate being removed.'

F 5 shows in elevation a single heating pipe.

The'walls of the furnace a consist of refractory material. On the innerSurfaces of the walls heating pipes b', b2 are arranged. The heatingpipes o are of trapezoidal cross section. so that the adjacent faces oftwo heating pipes are inclined with regard to one another, ,the heatbeing consequent] well transmitted in inward direction. Be-l tween twoadjacent heating pipes b air gaps are formed which extend .into the walla of the furnace and prevent 'a direct contact and a direct transmissionof heat from one pipes extend ypreferably through openings in theceiling of the furlos 'f granular resistance material.

al is inserted through the bottom of the pipe.`

heating pi to the other and consequently also mutua excessive heating ofthe heating pipes. These air gaps prevent farther the production ofshort-circuit between the heatl 1n pipes l he heating `ies b are ofrectangular cross Sectionan t e heating pipes b2 are of circularcross'section. Inone furnace only heating ipes of the same cross sectionare preferab y used; but heating pipes of different cross sections mightbe used, as shown, in the same furnace to ensure radiations of differentstrengths in the different parts of the furnace.'

In order t improve the Aradiation of the heat' from the walls, this heathaving been radiated from the heating-pipes b2 on the walls, the wallshave ribeshaped `projections'c. v Y Each hea-ting pipe consists ofl anouter pipe of refractory material being filled with rlhe upper end ofthe heating pipe is closed by a cap. f through which an electrode d isinserted. This cap may be omitted.

. The neck of thepipe is mounted inthe bottomv of the furnace a theupper-end of the pipe extending through the topr plate g of the furnace.If one of the pipes should be dam-aged it may be removed from thefurnace in upward'direetion after the electric connection has beenloosened, a new pipe being inserted instead. I i

The bottom is heated by means of resistance material mounted in acavity-of the bottom, Current is supplied to this resistance material byelectrodes d. The resistance material in the bottom is covered by arefractory plate z' whichiprevents the access of air to the resistancematerial. The opening 7c for the door is closed by a plate Z. In

An electrode "furnace of circular cross section is otherwise -similar tothat of the form ,of construction shown in Figs. 1-3.

1 In an electric furnace,v resistance ele- `ments comprising casings ofrefactory material and granular resistance material. therein, saidcasings having their llateral faces inwardly inclined whereby wedgedshaped air gaps are formed between said resistance elements. n

In an electric furnace, resistance velements comprising casings ofrefractory material and granular resistance material therev in, saidcasiugsbeing disposed along the furnace vwalls, and 4air gaps betweensaid casings and extending into the furnace walls.

3. In an electric furnace, resistance ele monts comprising casings ofrefractory material and granular resistance material therein, saidcasings being disposed along the furnace walls and having inwardlyinclined faces whereby wedged shaped air gaps are `formed between saidresistance elements1 said air gaps being extended into 'the furnacewalls. p y

In testimony whereof I affix my signature in presence of two witnesses.

HEINRICH SEIBERT. Witnesses:

E. E. KURSCHFURT, E. H. GERMAN.

